I'm getting a strange vibration sound from the rear, only at a certain rpm in 1st, or maybe it's just most noticeable at that time. If I run through first normally into second, all sounds normal. It's when I linger in first between 3k - 5k rpms, I am hearing it. Any ideas??

 

Wheel bearings come to mind.

When I'm just coasting down the road mine make a tad bit of noise. Makes me glad I've fabricated a puller and press that get the job done super fast. Tried it out on Odurandina's 968 / LS7 a few months ago. Will not be long until I do my own.


Or it could be your shifter linkage, but I think that is only on the G50 cars.

 

If it was wheels, then I think it would always make noise, no? It's just noticeable at a certain rpm in 1st.

 

All depends on the load you are putting on them. That's why sometimes failing bearings only make noise when you are turning.

 

I actually found this thread on another forum, which more accurately describes what I'm hearing. This make sense given a 915 tranny? I've read the G50 differs in the linkage or something to that extent. Here's the quote

"mine has just developed a 'whine' in 3rd - it sounded more like holding a coin against a spinning disc brake/flywheel thingy as it turned (ie it was a metalic grindy/scorey noise) but it was only in 3rd, not 2nd or 4th ? Turned out to be a perished bush/washer thingy (im so technical!) in gear shaft linkage, making the shaft press rub against the tunnel side" end quote

 

Also maybe gears in the trans have some tolerance slop? If you're coasting with no real load on them they might rattle, though that sort of thing crops up more at low rpm.

 

I really only hear the noise under load, which is in lingering in the powerband in first, like between 3-5k. Mechanic / owner of shop is going to "live" w/ car for this week. He's going to take it to and from home / work and try to pinpoint this noise and also the idling issue I've been having.